This invention lies in the area of cardiac pacers and method of operation of same, with means for varying operating characteristics of one or more circuits and, in particular, pacers and other implantable devices with microprocessor control for switching the characteristics of one or more circuits on a predetermined basis.
It is known that pacemakers, and other implanted devices generally, have a need to respond to different types of sensed signal information. Thus, for example, in the pacemaker embodiment, where the implanted device operates on a cyclical basis, it may be desirable to change the operating characteristics of the circuit or circuits which sense the patient-generated signals, either within each cycle of operation, or over a period of time. In the prior art it is well known that parameters can be programmed externally, but such programming does not meet the objective of this invention for changing one or more circuit characteristics during each cycle, nor does programming provide for automatic response to sensed patient conditions.
While it is known that programmable circuits are available in other art areas, there has been no use or incorporation of controllable or switchable circuits into implantable devices for more efficient use thereof. For devices such as cardiac pacemakers, muscle stimulators, automatic drug dispensers, etc., there is a substantial need for the advantages to be gained by proper use of automatic switching, or by controlling the characteristics of circuits, e.g. changing filter characteristics. By use of a microprocessor incorporated with the implanted device, it is possible to optimize circuit operation in a manner which has heretofore been unavailable to the art.